1. Field of the Invention
The present invention was developed to safely reduce the rolling resistance of a vehicle, thereby increasing gas mileage. For this invention increasing gas mileage or miles per gallon will be used but in the case of electric vehicles one would substitute “increasing miles per charge”.
The present invention relates to a pneumatic or gas-filled tire and wheel assembly for attachment to any and/or all hubs of a motor vehicle both front and rear. For the purposes of this invention, a tire that has been mounted on a rim is defined as a wheel. When the three wheels outlined in the invention have been assembled they are defined as the TTAssembly (Triple Tire Assembly). Each TTAssembly comprises two interchangeable small diameter wheels and one large diameter wheel. See FIG. 8. The two interchangeable small diameter wheels are mounted on each side of the large diameter wheel creating the TTAssembly. See FIG. 5.
The TTAssembly must be mounted in pairs and would be mounted on each hub of the vehicle for maximum efficiency. See FIG. 9. The TTAssembly could also be mounted on just the front hubs of the vehicle, but the efficiency would be greatly reduced.
Since it is well known that narrower tires produce less rolling resistance and hence save gas, they are an obvious choice for the large diameter tire. It is also well known that the more tire surface area contacting the road, the more traction and support the vehicle will have. This makes for a safer driving experience, but will reduce gas mileage. It is also well known that a tire assembly with three separate air chambers is safer than a tire with two or one air chambers, thus this invention eliminates the need for a spare tire. While each individual choice above may seem obvious, developing a practical combined solution focused on increasing gas mileage while maximizing safety has eluded those knowledgeable in the subject for years. This invention is the perfect solution to maximize gas mileage and reduce cost while providing safety.
The operation of the TTAssembly is uniquely simple. As the vehicle travels in a straight line, the large diameter wheel of the TTAssembly contacts the roadbed. The narrow footprint of the large diameter wheel maximizes the gas mileage. As the vehicle enters a turn, the TTAssemblies on the front of the vehicle are tilted either left or right due to a camber change of the vehicle. See FIG. 2. When the camber change is large enough it causes one of the small diameter wheels of each of the TTAssemblies on the front of the vehicle to contact the roadbed in addition to the large diameter wheel. This increases each TTAssemblies footprint on the roadbed making the turning of the vehicle safer. This transfer to the wider footprint occurs passively, without electronic, computer, or human-controlled mechanisms or pumps, and is seamless to the driver. If the vehicle weight is within its operating parameters and the tires selected are based on the manufacturers recommendations this passive transfer will be irrespective of the weight of the vehicle during normal operation. In panic or emergency stops all large diameter tires in the TTAssemblies will experience deformation, see FIG. 10, due to the braking forces on the front tires and braking forces on the rear tires. These braking forces are at the roadbed level. The inertia of the vehicle acting against the braking forces creates a rotating tendency, or torque, about the center of gravity of the vehicle. While the downward force on the front tires increases, the weight of the vehicle has not increased. In the case of a four wheel vehicle, that would put all twelve tires in the TTAssemblies in contact with the roadbed. Since it is well known that approximately 50% of the weight on the rear axle of the vehicle is transferred to the front tires during a hard stop, having the TTAssembly on all hubs of the vehicle is optimum.
The TTAssembly also offers a major benefit to the vehicle owner and the tire stores. Since the two smaller diameter wheels are interchangeable, it would be impossible to mount them on a vehicle incorrectly. Money would be saved because inventory could be reduced up to 60%, no spare tire is required, significant increase in miles per gallon is realized and there is reduced wear on the smaller diameter tires.
Additional benefits to the TTAssembly come in the form of types of tires that could be used. If snow tires were mounted on the inboard and outboard rims, the resulting ride would be much smoother and quieter than that of a regular snow tire during straight line driving. Chains could be mounted on the inboard and outboard tires and would not contact the road until the vehicle was turning or the snow was deep enough to contact the smaller diameter wheels. This would eliminate the daunting task of putting on chains in the snow. Four wheel drive or off-road vehicles could also use the TTAssembly. This would allow them to drive on paved roads to their destination and then drive off-road, like on sand dunes, where the wide or paddle-wheel or other fancy smaller diameter tires could come into contact with the surface. This would eliminate the need for trailering the vehicle or changing tires once the destination was reached. Military vehicles would benefit from reduced exposure to flat tires and could drive into non-paved areas without stopping to change tires. For sports cars, having the large diameter tire of the TTAssembly be the same width or even wider than the small diameter inboard and outboard tires might be appropriate in some instances. It would reduce gas consumption somewhat and eliminate the need for a spare tire in a typically miniscule trunk.
2. Description of Related Art
A high profile or narrow taller tire may be defined as a tire having a comparatively high aspect ratio, or height-to-width ratio, where the height is the distance measured radially from the tire's outer diameter to the rim opening or rim seat. A narrow, taller tire is preferred where fuel economy, low road noise, and ride quality are the main operational concerns. However, narrow taller tires do not have ideal handling characteristics in terms of steering, acceleration, and braking in aggressive driving conditions such as rainy conditions, sudden obstacles, or other condition where a large degree of safety or performance margin is required. A wider tire, also referred to as low profile or low aspect ratio, may be preferred for vehicles intended for high-performance handling, aggressive driving conditions or carrying heavy loads. However, wider tires or dual tires do not perform well in terms of fuel economy, road noise, ride quality, and tire wear. Tire selection typically involves compromise, sacrificing certain desirable performance characteristics for others such as performance or safety verses gas mileage. Vehicles such as family sedans or mini vans, which are mainly intended for comparatively sedate driving styles and straight-line highway driving, are typically fitted with softer riding taller tires with an aspect ratio of 70% to 80%. These narrower taller tires give them better gas mileage. Sports cars are commonly fitted with wider low aspect ratio tires in the 30% to 50% range. Trucks use dual tires on the rear wheels which are inherently wider to add stability, increase load capacity and improve traction and the like. Each of these compromises is acceptable when the vehicles in question are being operated according to their primary intended functions, but both suffer from significant drawbacks when operational conditions change. A vehicle riding on narrow taller tires requires slower speeds to navigate narrow, winding roads where tight cornering and hard braking may be required, especially when traction is poor due to rough, wet, or icy road surface conditions. In contrast, a vehicle with wider tires or dual rear tires generally handles much more responsively under such adverse conditions than if it had taller narrower tires, but it will give a rougher and noisier ride, with poorer fuel economy.
Prior art discloses numerous attempts to provide vehicle tire systems that use multiple-tire assemblies to adapt to different operating conditions. Elkow (U.S. Pat. No. 6,615,888) discloses a variable diameter wheel apparatus that uses a pump to inflate or deflate each tire independently to achieve optimum performance from a multiple tire arrangement. Sensors monitor selected operational parameters of the vehicle and transmits corresponding signals to a computer that selects an optimal tire configuration. Blomquist (U.S. Pat. No. 2,751,959) discloses a tire-and-wheel assembly having a selectively-inflatable auxiliary tire coaxially on a specialized telescoping rim and axle assembly, disposed between two conventional tires. The auxiliary tire has an accordion-like construction. The diameter of the auxiliary tire when un-inflated is less than that of the two conventional tires, so the auxiliary tire is not in contact with the road surface when it is un-inflated. When inflated, its diameter expands to match that of the conventional tires, and it also expands laterally, displacing the outboard conventional tire further outboard. Accordingly, inflation of the auxiliary tire greatly increases the total width of the wheel assembly and the total area of tire contact with the road surface, thereby providing improved traction. O'Brien (U.S. Pat. No. 5,788,335, U.S. Pat. No. 5,810,451, U.S. Pat. No. 6,022,082) discloses a studded, selectively inflatable auxiliary tire of specialized construction that is coaxially disposed between two conventional rear tires. As in Blomquist, the un-inflated diameter of the auxiliary tire in the O'Brien patents is less than that of the conventional tires. Upon inflation, the auxiliary tire expands in diameter, but does not expand laterally as in Blomquist, until it substantially matches the diameter of the conventional tires, such that the studs of the auxiliary tire may engage the road surface. The auxiliary tire thus must be manually inflated or deflated, to suit particular road conditions.
The inventions disclosed in the O'Brien patents cited above are directed primarily to providing rear wheel enhanced traction on slippery road surfaces, with the means for providing enhanced traction. This functionality is not passive. It requires the driver to stop and physically make changes to the vehicle to change from one state to another. It would be reckless to drive a vehicle on a clear dry road with the studs engaged. The studs would tear up the road until they were worn down, which would happen quickly, rendering the traction device useless. If the traction device is engaged, i.e. expanded to larger than the inboard and outboard wheels, the vehicle will still ride on all three wheels. O'Brien states “The tire 24 is expanded such that the studs 20 will extend beyond the diameter of the wheels 12, 14 to engage the supporting surface (roadway). The wheels 12, 14 still supports the vehicle weight and the tire 24 provides the traction.” O'Brien's traction device is equivalent to adding chains to the outboard tire. It does not support any additional weight, requires a driver's interaction and will not increase gas mileage. Because the auxiliary tire is only used for traction and not for support, it would be obvious that the width of the auxiliary tire must be smaller than the width of the support tires as they are used for holding the side of the auxiliary tire. Otherwise the sidewall would buckle and traction would be non-existent. If the auxiliary tire were larger than the support tires the ability of the auxiliary tire to contract when not in use would compromise the ability to handle the torque required of a traction device.
The traction device rim outlined in the O'Brien patent has mounting holes that line up with the mounting lugs or bolts of the wheel housing. The additional thickness of the traction device rim, which allows for the mounting between two standard dual wheels, would require longer bolts from the hub. The rim would be custom for every configuration of dual wheels as the distance between the dual wheels is not consistent. In O'Brien's FIGS. 3, 5, 6 and 7 the rim is shown as flat. O'Brien's FIG. 5 shows that a spacer is used to allow enough space for the traction device to operate successfully. This traction device is not able to remove the heat build up from the traction device to allow it to operate at highway speeds, nor is it meant to. It is only good for providing studs, an alternative to chains that increase traction. Studded tires are allowed in 36 different states, and only between November 1st and March 31st. Alabama, Florida, Hawaii, Illinois, Louisiana, Mississippi, and Texas all ban studded tires completely. Revamping the studded to non-studded configuration while traveling in and out of these states would require a specialty tire service company and is not passive. The O'Brien patent would not work as the front tires of a vehicle. It requires the vehicle to have dual front tires with extended front axles to accommodate wheels with extreme positive offset that are expanded to fit the third tire in-between them. The additional cost of the tires, modifying the vehicle body as well as the strain on the vehicle components such as power steering and alignment components would not be feasible. On top of that, the turning radius of the vehicle quadruples making it almost impossible to drive except in a straight line.
Prior art discloses technology for increased traction and skid resistance on wet or icy roads while also addressing other objectives such as ride quality, fuel economy, or general handling characteristics. However, these attempts were different because they did not provide a safe tire assembly capable of travelling at highway speeds while delivering maximum fuel efficiency using tire assemblies with large and small diameter tires and a seamless, passive method of transfer between them.
Prior art discloses un-inflated or underinflated wheels that can be hazardous, can come loose from the rim, and get caught under one of the other functioning tires, creating a rollover situation. The designs add unnecessary weight, which decreases fuel efficiency, decreases braking ability, and could cause a rollover. If a pump fails, all four of the tires could be flattened, creating a crash prone scenario. If the computer, actuator, communication link, or any one of many sensors malfunctions, a life threatening condition arises. The central tire could expand as the vehicle goes around a sharp curve, removing all traction from the tires. The prior art involves complex traction mechanisms or tires of specialized construction with special sensors, computers, and pump configurations.
The Tawara patent (JP 58139802A) discloses a rear wheel assembly consisting of a two tire system with one large diameter tire and one small diameter tire. The purpose of the arrangement is to reduce wear on “double wheels for the rear wheels of a bus or the like” and as the weight of the vehicle increases, the smaller diameter tire contacts the road. The drawings for the Tawara patent show both rear wheels being the same width. Most prior art involves one or more conventional tires which are in load-bearing contact with the road surface at all times, regardless of whether the invention's particular traction enhancement or performance means are engaged, and regardless of the road conditions being travelled on. None of the prior art, except the Tawara patent provides a wheel/tire assembly that in itself provides a passive system that seamlessly transfers between large and small diameter tires at the precise instances or conditions required. The O'Brien patent requires that you stop and pump up or deflate the tire when conditions change. While Tawara does provide for passive transfer, it is based on changing the weight of the vehicle and will not change based on roadbed conditions, or vehicle direction change. In an emergency stop the Tawara patent becomes dangerous. Since it is the added weight in the vehicle that makes the second wheel contact the road surface, and since 50% or more of the weight is transferred to the front wheels in an emergency stop, the second wheel would be lifted off the ground reducing the frictional force on the rear wheels significantly increasing stopping distance. It cannot provide for optimum gas mileage. If the Tawara vehicle is lightly loaded, then it responds like a regular one wheel per hub vehicle. It would be obvious to one skilled in the art that a narrow tire on a high center of gravity vehicle, by itself, would be dangerous During a turn, the tall narrow tire would lower the friction side forces on the tire making a rollover more likely. This is especially true in a situation where narrow tires are used if the vehicle is top-heavy, such as a bus or a truck that would experience such stated vehicle weight increase that could deform Tawara's large diameter tire. It would be unsafe to operate with a high aspect ratio tire, therefore a wide tire would be required for the main roadbed-contacting rear wheels. Thus a significant gas savings cannot be achieved.
It would also be obvious to one skilled in the art that moving the Tawara patent idea to the front axle would be precluded. This is due to the fact that only one of the seldom used small diameter tires could contact the roadbed during a turn or obstacle avoidance maneuver causing a change in the tire width and frictional force on one side of the vehicle and not the other. This is also the case with the O'Brien patent as shown in his FIG. 6. This could result in a loss of control of the vehicle. This is often seen when a space-saver spare is used on one side of an axle, and is only condoned as a very reduced speed emergency tactic.
When the Tawara vehicle is loaded, both rear tires contact the road surface, giving more vehicle support and traction but completely eliminating any gas savings. This cannot be changed until the vehicle is unloaded.
Prior art also shows that most dual and triple wheel rims are focused on mounting dual wheels with enhancements in place of single wheels on the rear hubs of campers, light and heavy duty trucks for adding stability, increasing load capacity improving braking and traction and the like. These designs require heavy duty construction to accomplish the increase in load capacity and the wide track for added stability. Large heavy duty inner and outer rims with adaptors, sleeves, struts, baskets or cup like assemblies that allow access to inner rims are required to meet these expectations.
The solid rubber wheel (roue à bandage plein) described by Vaillant (FR 1066702A) in FIG. 3 could not be used on today's passenger cars where speeds of up to 80 MPH are attained. The diameter of the solid tire(s) would have to be at close to rim level to mitigate accidents while turning, meaning that it never contacts the road unless there is a flat tire. The width of the center tire in FIG. 3 can be larger than the inside and outside solid non-road contacting rubber wheels. It was designed to compensate for a flat tire where one could limp (less than 20 miles per hour) to a gas station to have it fixed. This is not an operational vehicle when the center tire is flat. He states that his invention protects the vehicle from projectiles that would impale a pneumatic tire. This was 1954, with large V8 engines where gas was cheap and horsepower was king. The leap from a device that must use solid rubber wheels to function as a “run flat” device located at or near the outside radius of the rim, to a device that requires pneumatic tires, that are in contact the road surface to increase gas mileage would not be predictable, but an accidental discovery, like vulcanization.
The TTAssembly invention is completely different. It is designed for all four vehicle hubs. Its main goal is not to carry additional weight or gain more traction but to safely increase miles per gallon. The invention is designed to replace a standard wheel, not require specially formed fenders or body parts to accommodate the additional width of a multiple tire system. The invention is fully reversible and could be bolted to the vehicle hub from either side. According to prior art, if the rims on a dual wheel system could be mounted in the reverse direction, the dual wheels would extend out further from the vehicle, thus producing undesirable performance characteristics.